We are often asked, especially by those relocating here from northern climates, is it necessary to drain sprinkler systems here in Texas. In most instances, the answer is no. However there are some exceptions.
Sprinkler systems are composed of two different types of lines. The supply, or lateral lines, connect the sprinkler heads to the main supply lines. These lateral lines, even those above ground, risers and other heads that are connected to it, most often should not freeze because they are not under constant pressureand water empties from the pipe when that particular zone of heads is turned off.
The lines susceptible to freezing are mainlines, those that are under constant pressure and/or above the ground.In situations where an above ground backflow preventer is used, there is an even greater danger of freezing. There are variations of above ground backflow preventers, but the most common are the RPZand APB.
RPZ backflow device
To reduce the possibility of freezing, the backflow device and the pipes leading to it should be well insulated. Additionally, for extra precaution, the device and those pipes can be drained to greatly reduce the possibility of freezing. Additionally many manufacturers produce an insulated covering or blanket, to better insulate the backflow device